Common Pitfalls

Avoid these common mistakes when writing tests:

1. Forgetting to Return in Async Tests

The test finishes before the promise resolves. Always return the promise:

# Wrong: promise resolves before test checks resultexport default {  fn: async () => {    const result = await someAsyncFunction()    // missing return!  },  expect: true,}# Correct:export default {  fn: async () => {    return await someAsyncFunction()  },  expect: true,}

2. Not Wrapping Callback Functions

# Wrong: function gets called immediatelyexport default {  fn: doSomething(),  // executes immediately!  expect: true,}# Correct: wrap in function to defer executionexport default {  fn: () => doSomething(),  expect: true,}

3. Mutating Shared State Between Tests

# Wrong: counter persists between testslet counter = 0export default [  { fn: () => ++counter, expect: 1 },  { fn: () => ++counter, expect: 2 }, // fails! counter is now 1]# Correct: use beforeEach to reset stateexport default {  beforeEach: () => { counter = 0 },  tests: [    { fn: () => ++counter, expect: 1 },    { fn: () => ++counter, expect: 1 }, // passes - reset before each  ],}

4. Using the Wrong Equality Check

# Wrong: checks reference equalityexport default {  fn: () => [1, 2, 3],  expect: [1, 2, 3], // fails! different arrays}# Correct: use @magic/types for deep comparisonimport { is } from '@magic/test'export default {  fn: () => [1, 2, 3],  expect: is.deep.equal([1, 2, 3]),}

5. Not Awaiting Async Operations

# Wrong: test finishes before promise resolvesexport default {  fn: () => {    setTimeout(() => {      // This never gets checked!    }, 100)  },  expect: true,}# Correct: return the promiseexport default {  fn: () => new Promise(resolve => {    setTimeout(() => resolve(true), 100)  }),  expect: true,}# Or use the promise helper:import { promise } from '@magic/test'export default {  fn: promise(cb => setTimeout(() => cb(null, true), 100)),  expect: true,}

6. Incorrect Hook Usage

# Wrong: before/after hooks on individual tests, not suitesexport default [  {    fn: () => true,    beforeAll: () => {}, // wrong! beforeAll is for suites    afterAll: () => {},    expect: true,  },]# Correct: hooks at suite levelexport default {  beforeAll: () => {},  afterAll: () => {},  tests: [    { fn: () => true, expect: true },  ],}